Better Laundry Detergient

Well Ian has the worst smelling poops, which Im told is very common for SBS. But due to his age he tends to well soil alot of outfits. We currently use Tide with Bleach and Scented Fabric softner but there is still a dingy smell to it unless Im washing 1/2 load like 3x. So my question is if there are any better detergients that anyone uses with this similar problem. Seems silly but I dont want Ian to smell funny, on top of the foul gas and poops.